The invention is directed to a method of preparing sulfenic acid chlorides and sulfenic acid esters with hydrolyzable silyl groups.
German-OS No. 19 06 521 teaches a method of preparing sulfenic acid chlorides (sulfenyl chlorides) in which an unsaturated organosilane compound is reacted with sulfur dichloride. At the same time, however, there must be accepted the addition of chlorine to one of the C atoms of the originally unsaturated bond in the compound.
N. Auner and J. Grobe (Z. anorg. allg. Chem. 500, 1983, pp. 132-160, especially p. 153) describe a similar SCl.sub.2 -addition, which, however, starts with 1,3-silacyclobutanes, whereby a sulfenyl chloride with only one hydrolyzable group on the Si atom can be obtained. Stacy U.S. Pat. No. 4,278,585 is directed to sulfenic acid esters which are extracted by the esterification of sulfenic acid chlorides formed in the reaction of mercaptan containing silyl groups with sulfuryl chloride in the presence of amines.
This method has the disadvantage that there can only be obtained a product mixture which is contaminated by numerous by-products and which is difficult to separate. Furthermore the use of amines as HCl receptors results in precipitates which are difficult to filter.
Sulfenic acid chlorides and sulfenic acid esters with hydrolyzable silyl groups are used in the preparation of polymers which can be hardened with moisture or vulcanized or are used as reinforcing additives in rubber mixtures containing silica and cross-linked with sulfur.
The invention has the task of preparing the mentioned chlorides and esters in good yields and in the form of pure products.